Sibutramine, N,N-dimethyl-1-[1-(4-chlorophenyl)-cyclobutyl]-3-methylbutylamine of formula (II); may be used for preventing or treating depression, Parkinson's disease and obesity (see GB Patent No. 2,098,602, Korean Patent Publication Nos. 90-00274 and 99-164435, and International Publication No. WO 88/06444). Further, sibutramine may be used for reducing the resistance to insulin or enhancing the resistance to sugar, and for preventing or treating such diseases as gout, hyperuricemia, hyperlipemia, osteoarthritis, anxiety disorder, somnipathy, sexual dysfunction, chronic fatigue syndrome and cholelithiasis (see U.S. Pat. Nos. 6,174,925, 5,459,164, 6,187,820, 6,162,831, 6,232,347, 6,355,685, 6,365,631, 6,376,554, 6,376,551 and 6,376,552).
However, since sibutramine has a low melting point, it is used as an acid-addition salt in the pharmaceutical application.
GB Patent No. 2,098,302 and Korean Patent Publication No. 90-00274 disclose methods for preparing sibutramine and an anhydrous hydrochloride form thereof as a pharmaceutically acceptable acid-addition salt. However, anhydrous sibutramine hydrochloride is highly hygroscopic. Accordingly, it is difficult to use anhydrous sibutramine hydrochloride in a pharmaceutical composition.
In order to solve the above problem, non-hygroscopic sibutramine hydrochloride monohydrate of formula (IV) was developed (see GB Patent No. 2,184,122 and Korean Patent Publication No. 94-08913), e.g., for treating obesity. 
However, sibutramine hydrochloride monohydrate of formula (IV) for treating obesity, e.g., Meridia and Reductil, has a relatively low solubility in water, for example 2.9 mg/ml at pH 5.2, which does not meet the lowest limit of the solubility desired of an active ingredient of a pharmaceutical composition (see Merck Index, 13th Ed, p1522).
Accordingly, there has been a need to develop a novel salt or hydrate of crystalline sibutramine, which is suitable for use in a pharmaceutical composition. The present inventors have therefore endeavored to develop sibutramine methanesulfonate hemihydrate, which has a high solubility in water and is non-hygroscopic, being stable under a high temperature/humidity condition.